Some more details may be needed.Is the bleeding fresh or more like menstrual bleeding?Have you had similar bleeding episodes after sexual arousal in the past-before child birth/before insertion of Nexplanon?
If it is after Nexplanon, this may be irregular uterine bleeding
due to the hormone.,may necessitate removal if it persists beyond 3 months
If the bleeding is fresh it has to be investigated to locate the site and to detect any lesion.Sexual arousal causing uterine bleeding may be possible in the early 40 days or so when the uterus
is yet to return to normalcy,not so late.
Hope my answer is useful to you.